1. Field of the Invention
The present invention relates to an optical fiber scanning apparatus including a frame body to which a magnetic field generation unit is disposed, and an optical fiber in which a permanent magnet is disposed and which emits light from a distal end portion, and an optical scanning type endoscope including the optical fiber scanning apparatus at a distal end portion of an insertion portion.
2. Description of the Related Art
An image pickup apparatus using an image pickup device such as a CCD or a CMOS image sensor simultaneously receives reflected light from a subject by many photodetectors arranged in a matrix shape, and acquires an object image. In the case of an endoscope which photographs a dark inside of a body, an image in a range illuminated by light from a light source is acquired.
In contrast, in an optical scanning type image pickup apparatus, while an object is scan-irradiated by a light spot, the reflected light is successively received, and an object image is prepared based on the light reception data.
For example, in the optical scanning type image pickup apparatus, by an optical fiber scanning apparatus two-dimensionally scanning a distal end portion of an optical fiber that guides light from a light source, scan irradiation of the light spot is performed.
Optical fiber scanning of the optical fiber scanning apparatus is performed by controlling magnetic application from a magnetic field generation unit to an optical fiber where a magnet is disposed, for example.
Further, in an endoscope, diameter reduction of a distal end portion is strongly demanded in order to reduce invasion. In order to reduce a diameter of an optical scanning type endoscope for which an optical fiber scanning apparatus is disposed at a distal end portion, the diameter reduction of the optical fiber scanning type image pickup apparatus is an important issue.
Japanese Patent Application Laid-Open Publication No. 2008-116922 discloses an optical fiber scanning apparatus using magnetic force. In the conventional optical fiber scanning apparatus, an optical fiber where a permanent magnet is disposed is arranged at a center of a magnetic field generation unit formed of four electromagnets (magnetic field generation portions) which are orthogonally arranged/oppositely arranged inside a cylinder.
In the optical fiber scanning apparatus, a coil of the electromagnet is a winding coil in which a copper wire is wound in an elliptic shape around an outer periphery of a magnetic core formed of a soft magnetic body.